pug skin problem

Hi, I have a 4yrs old pug. She does scratches sometimes and not crazy...usually she just scratch her sides and sometimes seems like she will scratch when she wants attentions. I noticed that she has some blackhead like on her pores and some areas has crusts like skin and there are brownish flakes. She is on revolution every month. I am not sure what it is. It doesn't seem to bother her much.